1. Field of the Invention
This invention relates to electronic communications systems for remote signaling to a telephone line over available AC power lines. More particularly, this invention relates to a wireless telephone connection system which provides both electric power line surge suppression and isolation circuitry to prevent degradation of the communication signal due to power line noise generated by nearby electrical equipment or electronic devices.
2. Description of Related Art
It is desirable in power line carrier communication systems to be able to electrically isolate the communications device, e.g., a telephone, a facsimile machine, and/or a modem, from power line noise induced by other electrical equipment on the same or a nearby circuit. Failure to consider and isolate electronics equipment from communications equipment, especially communications equipment which makes use of the power line as the communication medium, can cause the communication signal to become so degraded that the reliability of the communication channel is significantly reduced. Power line carrier communication systems offer significant advantages to standard wired or wireless radio type communications, including reduced costs, pre-existent wiring, no need for an allocation of limited radio frequency channels, and increased signal security.
A variety of power line carrier telephone voice and/or data communication systems have been developed and are used to facilitate telephonic communications in locations where little or no availability exists for dedicated telephone wires. While these devices provide a connection to the existing power lines they do not incorporate the filtering and isolation circuitry necessary to protect the voice and/or data signal from power line noise due to nearby equipment also plugged into the existing power lines. Surge suppression circuits in general are well known in the related art, as are isolation circuits. However, for optimum performance, surge suppression and isolation should be matched to the unique requirements of power line carrier communications and, to minimize ringing and other capacitive effects, should be placed in close physical proximity to the connection between the communications device and the power line.
The most common alternatives to the present invention are (1) ignoring the problem and attempting to operate in a potentially high noise environment; (2) using separate standard commercially available surge suppressors and/or isolators without accounting for the line matching and proximity issues; (3) designing custom isolation equipment for each site and attempting to tune such isolators to the power line environment.
A very wide variety of power line carrier communications devices, systems and methods have been previously disclosed, and could be considered related art, although not prior art. Each of which may address a particular power line carrier communication problem and each of which may, in certain instances, be used in combination with the present invention to improve power line carrier communications. For background material as to the previously disclosed devices, systems and methods concerning power line carrier communications, the reader is directed to the following United States and foreign patent documents: U.S. Pat. Nos. 2,510,273, 2,516,211, 2,516,763, 2,535,446, 2,567,908, 2,577,731, 2,654,805, 2,820,097, 2,828,363, 2,932,794, 3,045,066, 3,280,259, 3,334,185, 3,369,078, 3,399,397, 3,400,221, 3,475,561, 3,521,267, 3,529,216, 3,659,280, 3,693,155, 3,810,096, 3,818,481, 3,846,638, 3,852,740, 3,876,984, 3,911,415, 3,922,664, 3,924,223, 3,925,763, 3,925,728, 3,942,168, 3,949,172, 3,967,264, 3,973,087, 3,980,954, 4,012,733, 4,012,734, 4,016,429, 4,057,793, 4,058,678, 4,065,763, 4,107,656, 4,161,027, 4,173,754, 4,174,517, 4,218,655, 4,222,035, 4,239,940, 4,254,403, 4,307,380, 4,321,581, 4,323,882, 4,344,066, 4,357,598, 4,371,867, 4,377,804, 4,386,436, 4,400,688, 4,408,185, 4,408,186, 4,429,299, 4,433,326, 4,442,319, 4,471,399, 4,473,817, 4,475,193, 4,479,033, 4,495,386, 4,514,594, 4,523,307, 4,535,447, 4,538,136, 4,556,864, 4,556,865, 4,556,866, 4,559,520, 4,599,598, 4,609,839, 4,611,274, 4,633,218, 4,638,298, 4,638,299, 4,641,126, 4,641,322, 4,642,607, 4,644,321, 4,675,648, 4,701,945, 4,745,391, 4,745,392, 4,746,897, 4,749,992, 4,759,016, 4,763,103, 4,772,870, 4,774,493, 4,783,780, 4,788,527, 4,809,296, 4,829,570, 4,835,517, 4,845,466, 4,847,903, 4,864,589, 4,866,733, 4,890,089, 4,912,553, 4,962,496, 4,963,853, 4,968,970, 4,988,972, 4,995,053, 5,003,457, 5,032,833, 5,049,876, 5,063,563, 5,065,133, 5,066,939, 5,136,612, 5,151,838, 5,155,466, 5,168,510, 5,187,865, 5,192,231, 5,210,518, 5,241,283, 5,257,006, 5,262,755, 5,278,862, 5,289,476, 5,319,634, 5,327,230, 5,349,644, 5,351,272, 5,355,114, 5,357,541, 5,404,127, 5,406,248, 5,406,249, 5,410,292, 5,412,369, 5,424,709, 5,448,593, 5,452,344, 5,461,629, 5,463,662, 5,467,011, 5,471,190, 5,504,454, 5,530,737, 5,554,968, 5,559,377, 5,630,204, GB 544,243, GB 549,948, GB 553,225, GB 683,265, GB 1,393,424, GB 2,094,598, AU-B1-12,488/76, Canada 1057436, Canada 1216689, EPO 0 078 171 A2, EPO 0 555 869 A2, PCT/US83/01717, PCT/US90/02291, PCT/US90/06701, PCT/US92/08510, PCT/US93/04726, PCT/US94/03110, and PCT/US95/00354 each of which is hereby incorporated by reference in its entirety for the material disclosed therein. Applicant is aware of a large number of references to wireless but not power line carrier communication systems. Because the present invention relates primarily to power line carrier communications, applicant believes that wireless but not power line carrier references are not relevant to the consideration of this application.